Transmitting and recording method, reproducing method, and reproducing apparatus of information and its recording medium

ABSTRACT

A method of reproducing data from a recording medium, each of the data including reference time information indicating a reference time and including packet data, the method including: reproducing the data from the recording medium; obtaining a difference between respective reference times indicated by the reference time information of the reproduced adjacent data; rearranging the data on a time axis such that a time interval between adjacent data is equal to the obtained reference time difference; and outputting the rearranged data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 10/733,319,which is a continuation of application Ser. No. 10/252,581 filed Sep.24, 2002 (now U.S. Pat. No. 6,693,966), which is a continuation of Ser.No. 10/051,066, filed Jan. 22, 2002 (now U.S. Pat. No. 6,549,579), whichis a continuation of application Ser. No. 08/463,827, filed Jun. 5, 1995(now U.S. Pat. No. 6,438,172). This application relates to and claimspriority from Japanese Patent Application No. 06-136962, filed on Jun.20, 1994. The entirety of the contents and subject matter of all of theabove is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for recording compressedvideo and audio signals on a medium such as an optical disk or the likeand reproducing such signals from such a medium.

A compression of video and audio signals has been described in detail inJun Yonemitsu (editorial supervisor), “MPEG Technique,” pp. 19-21,published in Japan by Trikeps on Dec. 21, 1993. An example of an opticaldisk has been described in detail in Kenji Hayashi (editor and author),“CD-From Audio to Personal Computer,” pp. 84-89, published in Tokyo,Japan, by Corona Publishing Co., Ltd., on Jul. 25, 1990.

A compression method of the video and audio signals and a correspondingdecompression method have been described in the first reference listedabove. A signal recording format of a compact disc (CD) has beendescribed in the second reference listed above. However, a method ofeasily realizing a retrieving method when the compressed video and audiosignals are recorded on a medium and are reproduced therefrom is notdescribed.

In the case of reproducing the medium such as a CD or the like on whichthe compressed video and audio signals have been recorded in a datastream format as described in the “MPEG Technique” reference listedabove, a picture or a boundary of a group of pictures can be judged byreproducing the data stream and judging header information of a pack anda packet. In the case of recording a signal on the medium, however, inorder to improve an error resistance, an interleave process and an errorcorrection encoding process which are peculiar to the medium and a frameforming process involving addition of a sync signal and sub informationare ordinarily executed. When the picture or boundary of the picturegroup is judged by reproducing the data stream and judging the headerinformation of the pack and the packet, therefore, a position of apickup or the like which is reproducing data from the medium has alreadybeen deviated. Therefore, in the case of performing a retrieval, anediting operation, and the like on a picture or picture group unitbasis, a complicated control is needed to find a position of the pictureor boundary of the picture group on the medium, so that there is aproblem such that it takes a long time to find the position.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a transmitting and recordingmethod, a reproducing method, and a reproducing apparatus of informationwhich are suitable for retrieving and editing on a picture or picturegroup unit basis.

The above object is accomplished by a method whereby, when timesequential data of a pack is divided into a minimum unit of a datastructure which is peculiar to a medium and is transmitted or recordedon the medium, information indicating whether or not a picture or aboundary of a picture group exists in the minimum unit of the datastructure peculiar to the medium is described in a sub informationportion in a frame signal to be transmitted or recorded when a frameforming process that is peculiar to the medium is executed.

In the case of performing a retrieval, an editing operation, or the likeon a picture or a picture group unit basis, by reading the informationwhich was reproduced from the medium and was written in the subinformation portion in the frame signal peculiar to the medium andindicates whether or not the picture or the boundary of the picturegroup exists in the minimum unit of the data structure peculiar to themedium and by judging the information, a reproducing position on themedium at which to reproduce the picture or the boundary of the picturegroup can be accurately and easily detected. Thus, a complicated controlto find the position of the picture or the boundary of the picture groupis unnecessary, so that the picture or the boundary of the picture groupcan be retrieved at a high speed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an embodiment of a transmitting orrecording method of information according to the invention;

FIG. 2 is a block diagram and an explanatory diagram showing anotherembodiment of a recording method of information according to theinvention;

FIG. 3 is an explanatory diagram showing a reproducing method ofinformation according to the invention;

FIG. 4 is an explanatory diagram showing another embodiment of areproducing method of information according to the invention; and

FIG. 5 is a block diagram and an explanatory diagram showing anembodiment of a reproducing apparatus of information according to theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention will now be described with reference to thedrawings.

FIG. 1 shows an embodiment of the invention and shows a transmitting orrecording method of information. Reference numeral 1 denotes a packforming process of compression data; 2 a signal process that is peculiarto a medium; 3 a medium to transmit or record information; 4 compressedvideo data; 5 compressed audio data; 6 independent data such as data orthe like which is defined by the user; 7, 8, and 9 packet formingprocesses; 10 a pack forming process; 11 a process to divide timesequential data of a pack to a data structure that is peculiar to themedium; 12 main signal processes such as addition of an error correctioncode, interleave, and the like peculiar to the medium; 13 an extractingprocess of information indicating in which component element of a datastructure a boundary of a group of pictures is included when the timesequential data of the pack is divided to the data structure peculiar tothe medium; 14 a frame forming process for forming a frame signalpeculiar to the medium; 15 a process to add sub information to the framesignal; and 16 a process to add a sync signal to every frame of theframe signal.

A method of transmitting information or forming a recording signalaccording to the invention will now be explained herein below withreference to FIG. 1.

In the pack forming process 1 of compression data, a packet headerindicative of a head of the packet is added to each of the compressedvideo data, compressed audio data, and independent data, thereby formingpackets. Each packet is time divided, one or more packets are collected,and a pack header indicative of the head of the pack and informationindicative of a reference time are further added, thereby constructing apack. In the signal process 2 peculiar to the medium, the timesequential data of the pack is first divided to the data structurepeculiar to the medium.

When dividing, an extracting process of information indicating in whichcomponent element of the data structure the boundary of the picturegroup is included is performed. The divided time sequential data of thepack is subjected to signal processes such as addition of an errorcorrection code, interleave, and the like in order to enhance an errorresistance in accordance with a signal processing format peculiar to themedium. In order to transmit or record the signal processed data, aframe forming process peculiar to the medium according to a frame formatis performed. In the frame forming process, sub information and a syncsignal indicative of the head of the frame are added to the data whichwas subjected to the signal processes peculiar to the medium, therebyforming a frame signal.

According to the invention, information indicating in which componentelement of the data structure peculiar to the medium the boundary of thepicture group is included is inserted in the sub information of theframe signal at the time of the frame forming process. If there is achannel code modulation rule which is suitable for recording ortransmitting data for the frame signal and which has been decided in themedium and which is peculiar to the medium, the channel code modulationaccording to the modulation rule is executed for the data. If there isno channel code modulation rule, data is transmitted or recorded as itis by the medium.

According to the invention, the information indicating whether or notthe head of data (for example, a group of pictures) of a certain unit ofthe compressed video data is included in the minimum unit of the datastructure peculiar to the medium can be transmitted or recorded by usingan area to transmit or record the sub information which is differentfrom an area to transmit or record main information in the frame signalpeculiar to the medium.

Another embodiment of the invention will now be described with referenceto FIG. 2. The embodiment relates to a case where the invention isapplied to a compact disc (CD), a CD-ROM, or a system having a datastructure and a frame format which are equivalent to those of theCD-ROM.

In FIG. 2, reference numeral 20 denotes time sequential data of a pack.A boundary between B and C indicates a boundary of a group of pictures.A head of the C portion denotes a head of data of the picture group.Reference numeral 21 denotes a data structure which is peculiar to themedium; A a header section including a sync signal or the like; B and Cdata to which the time sequential data of the pack is divided and isallocated and which is equivalent to the B and C portions of the timesequential data of the pack; and D other data including a marginsection. Such A, B, C, and D portions indicate minimum units of the datastructure peculiar to the medium and are defined as one block. Accordingto the invention, the number of bytes of one block is set to 2352 bytes.

Reference numeral 22 denotes a frame signal peculiar to the medium; SY aframe sync signal; SUB a subcode as sub information; and 23 a maininformation portion in the frame signal. In the embodiment, the maininformation portion 23 has a total of 32 bytes including 24 bytes ofdata and eight bytes of an error correction code (ECC). It is assumedthat one frame is constructed by such a frame sync signal, subcode assub information, and main information. Reference numeral 24 denotes adata structure of the subcode. The subcode is formed by eight kinds ofcodes such as P, Q, R, S, T, U, V, and W each having a code length of 98bits. Data of eight bits obtained by collecting one bit from each codeis inserted in the SUB portion in the frame signal.

A recording method of the embodiment will now be explained. The timesequential data of the pack is divided every number of bytescorresponding to the number of bytes of the data portion of the block asa minimum unit of the data structure peculiar to the medium, therebyallocating data to the data portion of each block. Upon allocation, itis detected that the boundary between the picture groups B and C existsin the block. A code indicative of the presence of the boundary iswritten, for example, in the Q code in the subcode. At the same time,the block formed data is subjected to the signal processes such asaddition of an error correction code, interleave, and the like peculiarto the medium. When the signal processed data is frame formed, such datais allocated to the main information portion of the frame signal.

At the same time, the subcode is allocated to the SUB portion by theforegoing method. As mentioned above, the information indicative of theboundary of the picture group can be written in the subcode portion ofthe frame signal. The frame signal constructed as mentioned above issubjected to, for example, an 8-14 modulation (EFM) such that eight bitsare allocated to 14 bits and, after that, the signal is recorded on amedium such as a CD or the like. According to the invention, informationindicating whether or not the head of the picture group of thecompressed video data is included in the block as a minimum unit of thedata structure peculiar to the medium can be recorded on a CD, a CD-ROM,or a system having a data structure and a frame format which are similarto those of the CD-ROM by using an area to record the sub information inthe frame signal peculiar to the medium.

The embodiment has been explained with respect to the case where theinformation indicative of the presence of the boundary is described inthe subcode Q. However, even if such information is described in any oneof the codes P, Q, R, S, T, U, V, and W without limiting it to the Qcode, a similar effect is obtained. For example, a data start flag isdescribed in the P code in the present CD. Information indicative of thepresence of the boundary can be described in place of such a flag or ina portion of such a flag. By describing the serial number or an addressof the head of the picture group of the compressed video data instead ofthe information indicative of the boundary, an even more accurateretrieval can be performed upon reproduction.

By not only describing the information indicative of the boundary andthe serial number or address of the head of the picture group of thecompressed video data but also simultaneously adding and describing aCRC code to detect reproduction errors of those data, a degree ofaccuracy of those data which are reproduced at the time of the retrievalcan be improved. In the case where the information indicative of theboundary or the serial number or address of the head of the picturegroup of the compressed video data is recorded in the Q code, bydescribing them in place of the portion in which PMIN, PSEC, and PFRAMEindicative of the minute, second, and frame of the reproducing time havebeen written in the present CD, the reproduction errors can be detectedby the CRC code of the Q code in this state. Although graphicinformation has been described in the codes R, S, T, U, V, and W in thepresent CD, the information can be also described in such portions by amethod similar to that of the P code described above.

Another embodiment of the invention will now be described with referenceto FIG. 3. FIG. 3 shows a reproducing method according to the invention.Data reading intervals shown by 31 and 33 are intervals during which areproducing apparatus reproduces data on a medium. A portion indicativeof a high speed movement of a data reading position 32 is an intervalduring which the reproducing apparatus moves the reproducing position ofdata on the medium for a high speed retrieval. After the data readingposition has been moved at a high speed upon high speed retrieval, thereproducing apparatus retrieves a target position on the medium whilerepeating the operation to read data.

According to the invention, in such a data reading interval, informationwhich has been written in the sub information in the frame signalpeculiar to the medium and which indicates whether or not the head ofthe data (for example, a picture group) of a certain unit of thecompressed video data is included in the minimum unit of the datastructure peculiar to the medium is judged and, on the basis of suchinformation, the boundary of data of a certain unit of the compressedvideo data can be retrieved from the medium at a high speed. Accordingto the embodiment, there is an effect such that the boundary of the dataof the certain unit of the compression video data can be retrieved fromthe medium at a high speed.

Another embodiment of the invention will now be described with referenceto FIG. 4. FIG. 4 shows a reproducing method according to the invention.The embodiment relates to a case where the reproducing method of theinvention is applied to a CD, a CD-ROM, or a system having a datastructure and a frame format which are similar to those of the CD-ROM.In FIG. 4, the same component elements as those in FIGS. 2 and 3 aredesignated by the same reference numerals.

In a manner similar to the embodiment shown in FIG. 3, the reproducingapparatus retrieves a target position on the medium while repeating theoperation to read data after the data reading position has been moved bymoving a pickup at a high speed upon high speed retrieval. A framesignal which is reproduced from the disk for the data reading intervalis the same signal as the frame signal shown in FIGS. 2 and 4.

As for the subcode, the subcodes each comprising eight bits written ineach frame for 98 frames are collected, thereby reproducing eightsubcodes of P, Q, R, S, T, U, V, and W in which one code consists of 98bits. Information which has been described in any one of those subcodesand indicates whether or not the head of the picture group of thecompressed video data is included in the block as a minimum unit of thedata structure peculiar to the medium is reproduced and a boundary ofthe picture group is judged, so that the boundary of the picture groupcan be retrieved at a high speed. According to the embodiment, there isan effect such that the boundary of data of a certain unit of thecompressed video data can be retrieved from the medium at a high speed.

Another embodiment of the invention will now be described with referenceto FIG. 5. FIG. 5 shows a reproducing apparatus according to theinvention. This embodiment relates to a case where the reproducingapparatus of the invention is applied to a CD, a CD-ROM, or a systemhaving a data structure and a frame format which are similar to those ofthe CD-ROM. In FIG. 5, reference numeral 51 denotes an optical disk; 52a signal processing section peculiar to the medium; 53 a subcode judgingsection; 54 a pickup control section; 55 a pickup; 56 a memory; 57 awrite address generating section; 58 a read address generating section;59 an address comparator; 60 an output time adjusting section of timesequential data of a pack; 61 a reference clock; and 62 a clock peculiarto the medium.

The operation at the time of a high speed retrieval will be firstdescribed. Upon high speed retrieval, a frame signal reproduced from theoptical disk 51 in the data reading interval is inputted to the signalprocessing section 52 peculiar to the medium, thereby separating asubcode and main information on the basis of a sync signal in the framesignal. The subcode is inputted to the subcode judging section 53,thereby judging whether or not the subcode indicates a boundary of apicture group. When the subcode does not indicate the boundary of thepicture group, the pickup 55 is moved at a high speed by the pickupcontrol section 54 and the judgment of the subcode is repeated. In thecase where the subcode does indicate the boundary of the picture group,reproduction is performed. As mentioned above, the retrieval can beperformed on a picture group unit basis.

The operation upon reproduction after completion of the retrieval willnow be described. The reproduced frame signal is inputted to the signalprocessing section 52 peculiar to the medium and the subcode and themain information are separated on the basis of the sync signal in theframe signal. After that, the main information is subjected to processessuch as error correction, deinterleave, and the like, therebyreproducing data of a block structure as a data structure peculiar tothe medium. The data of the block structure is stored into the memory 56in accordance with a write address which is generated by the writeaddress generating section 57 on the basis of the clock 62 peculiar tothe medium and the reference clock 61. The data stored in the memory 56is read out in accordance with a read address which is generated by theread address generating section 58 on the basis of the reference clock61 and is inputted to the output time adjusting section 60 of the timesequential data of the pack.

The write address and read address of the memory are always compared bythe address comparator 59. When the write address differs from the readaddress by a predetermined amount or more, the pickup 55 is controlledby the pickup control section 54 to temporarily stop the reproduction. Aspeed to read the data from the optical disk 51 is always set to beequal to or larger than the maximum data transfer rate of the timesequential data of the pack and the reproduction control described aboveis executed, so that an excessive data or a lack of data between thereproducing apparatus and a decoding apparatus of the time sequentialdata of the pack to which an output of the reproducing apparatus isconnected can be absorbed.

The data read out from the memory 56 is subjected to time basecorrection by the output time adjusting section 60 of the timesequential data of the pack. Reference numeral 63 shows a time basecorrection of the time sequential data of the pack. In the output timeadjusting section 60 of the time sequential data of the pack, a timeinterval between the heads of adjacent packs is corrected with respectto the time base so as to be almost equal to a difference between thereference times in accordance with the reference time described in everypack of the data read out from the memory 56. Since an amount of data ofone pack may be different for every pack, the data is outputted at themaximum data transfer rate in the time sequential data of the pack. Inthe case of a pack having a small amount of data, invalid data isoutputted in the portion between the end of the pack to the head of thenext pack or the data is outputted so as to indicate that such a portioncontains invalid data. For instance, such a process can be realized by amethod such that a signal indicative of valid or invalid data andsynchronized with the data is generated together with the data, anidentification signal is added to the invalid data portion, or the like.According to the embodiment as mentioned above, the reproducingapparatus which can retrieve the boundary of the picture group at a highspeed and can perform a normal reproduction can be constructed.

Explanations will now be made with reference to FIG. 5 with respect to acase where when a video signal is compressed, for example, encoded datais recorded on an optical disk while changing a data compression ratiofor every picture group and is reproduced by the present method.

A Group of Pictures (GOP) is constructed as a picture group by usingseveral video frames as a unit. A compression ratio is changed on a GOPunit basis, thereby compressing the video signal. The compressed videosignal is subsequently divided into several packs. A reference timesignal is added to the head of the pack and the pack is recorded. On theoptical disk 51, the recording is executed at a constant recordingdensity irrespective of the packs of the GOP of different compressionratios.

Upon reproduction, an output time of the time sequential data of thepack is adjusted so that a time interval between the heads of the packsis equal to a time difference between the reference time signals addedto the heads of the packs.

By executing the reproduction as mentioned above, the data encoded sothat the compression ratio of the data is changed on a GOP unit basiscan be also accurately reproduced.

Although the embodiment relates to an example of the case where one GOPis set to one pack, in the case of recording data of one GOP by dividingit to several packs, the data can be also reproduced in a similarmanner.

According to the invention, the information indicating whether or notthe head of data (for example, the picture group) of a certain unit ofthe compressed video data is included in a minimum unit of the datastructure peculiar to the medium can be transmitted or recorded by usingan area to transmit or record the sub information which is differentfrom an area to transmit or record the main information in the framesignal peculiar to the medium. According to the invention, the boundaryof the data of a certain unit of the compressed video data can beretrieved at a high speed from the medium. Further, the reproducingapparatus which can retrieve the boundary of the picture group at a highspeed and perform a normal reproduction can be constructed.

While example embodiments may be described herein, it is understood thatsuch is presented by way of illustration only, and are not to be takenas limiting or exhaustive in any way. Many modifications, adaptations,variations and equivalents are apparent as being well within the scopeof the appended claims.

1. (canceled)
 2. An apparatus for recording and reproducing digitallycompressed data in the form of divided data to and from a recordingmedium, comprising: a data processing circuit which adds reference timeinformation indicating an output reference time during a reproducingprocess to each of the divided data in the digitally compressed data; anerror correction code adding circuit which generates an error correctioncode from the divided data with the reference time information, and addsthe generated error correction code to the divided data with thereference time information; a recording circuit which records thedivided data with the reference time information and the errorcorrection code in the recording medium; a reproducing circuit whichreproduces the divided data with the reference time information and theerror correction code from the recording medium; an error correctioncircuit which performs error correction using the reproduced errorcorrection code on the reproduced divided data and the reproducedreference time information; and a rearranging circuit which rearrangesand outputs the reproduced and error-corrected divided data on a timeaxis according to the reproduced and error-corrected reference timeinformation, such that a time interval between adjacent divided data asoutputted from the rearranging circuit is equal to a time intervalbetween respective output reference times of the adjacent divided data.3. A method of recording and reproducing digitally compressed data inthe form of divided data to and from a recording medium, comprising:adding reference time information which is used for rearranging a timeinterval between reproduced divided data to each of the divided data inthe digitally compressed data; generating an error correction code fromthe divided data with the reference time information and adding thegenerated error correction code to the divided data with the referencetime information; recording the divided data with the reference timeinformation and the error correction code in the recording medium;reproducing the divided data with the reference time information and theerror correction code from the recording medium; performing errorcorrection using the reproduced error correction code on the reproduceddivided data and the reproduced reference time information; andrearranging and outputting the reproduced and error-corrected divideddata on a time axis according to the reproduced and error-correctedreference time information.
 4. An information recording media in whichdigital information is recorded, wherein the digital informationincludes: plural piece of divided data in digitally compressed data;reference time information indicating an output reference time during areproducing process, which is added to each of the divided data; anderror correction data added to the divided data with the reference timeinformation, which is used for error correction of the divided data withthe reference time information.